Hyaluronic acid is a naturally-occurring polysaccharide containing alternating N-acetyl-D-glucosamine and D-glucuronic acid monosaccharide units linked with beta 1-4 bonds and the disaccharide units linked with beta 1-3 glycoside bonds. It occurs usually as the sodium salt and has a molecular weight range of about 50,000 to 8xc3x97106.
The joint cavity or synovium is filled with synovial fluid which is predominantly made up of hyaluronic acid (HA). The HA of the synovium is produced primarily by the synoviocytes that line the intima layer of the synovium, and proteins and nutrients that are drawn from the lymphatic system. The synovial fluid is a liquid form of an extracellular matrix that maintains the synovium volume and hydrostatic pressure, provides chondrocytes in the avascular particular cartilage with a steady flow of nutrients, lubricates the cartilage surface, and cushions the synovial tissue from the deforming forces of movements, (Unsworth, A., xe2x80x9cMechanics of Human Jointsxe2x80x9d, (eds, Wright, V., and Radin, E. L.), pp 137-162, Marcel Dekker, New York, 1993). The rheological properties of synovial fluid are the result of the intricate meshwork of high molecular weight HA and its interaction with water molecules. It is a high molecular weight polymer made up of repeating disaccharide units of N-acetyl-glucosamine and glucuronic acid, Meyer, K., and Palmer, J. W., J. Biol. Chem. 107: 629-634, 1934.
The molecule is synthesized at the plasma membrane by the recently cloned hyaluronan synthase complex (Naoki, I., and Kimura, K., J. Biol. Chem., 271: 9875-9878, 1996 and Spicer, A. P. and McDonald, J. A., J. Biol. Chem., 273: 1923-1932, 1998). In a typically newly synthesized chain, upwards to 5000 disaccharide""s units are present, though it is currently unclear how the newly synthesized chain lengths are determined. Hyaluronan turnover in normal human synovial fluid is estimated to be approximately 20 hours, (Laurent, T. C., Laurent, U. B. G., and Fraser, J. R. E., Ann. Rheum. Dis., 54: 429-432, 1995).
Osteoarthritis (OA) is a common joint disease of unknown etiology. The pathology of OA is characterized by a progressive loss of the particular cartilage of synovial joints with concomitant bony changes, including sclerosis and osteophyte formation (Yelin, E., xe2x80x9cOsteoarthritisxe2x80x9d (eds. Brandt, K., Doherty, M., and Lohmander, L. S.), pp. 23-30, Oxford University Press, New York, 1998; Flores, R. H., and Hochberg, M. C., xe2x80x9cOsteoarthritisxe2x80x9d (eds. Brandt, K., Doherty, M., and Lohmander, L. S.), pp. 1-12, Oxford University Press, New York, 1998). In some cases, hyperthrophy of the marginal and underlying bone, mild synovitis and capsular thickening are observed (Flores et al.). Initiation events for OA are unknown but recent findings indicate that the onset of this disease is highly dependent on the balance between mechanical stability of the joint and the degree of mechanical insult or injury. It has been postulated that mechanical instability of the joint will lead to a failure of the resident cartilage cells, known as chondrocytes, to maintain the balance between synthesis and degradation of the extracellular matrix. Ultimately, this homeostasis fails and the degradation process begins to outweigh new synthesis (Lohmander, L. S., xe2x80x9cOsteoarthritic Disordersxe2x80x9d (eds Kuettner, K. E., and Goldberg, V. M.), pp. 459-474, The American Academy of Orthopedic Surgeons, Rosemond 1995). The disease is particularly debilitating and disabling and is not easily treated at the time of detection. Early diagnosis is often difficult because of:
1) the lack of sensitive and cost permitting methods for early detection; and
2) the tendency of patients to attribute joint pain to the gradual but inevitable part of aging (Brandt, K., Lohmander, L. S., and Doherty, M., xe2x80x9cOsteoarthritisxe2x80x9d (eds. Brandt K., Doherty, M., and Lohmander, L. S.), pp. 70-74, Oxford University Press, New York, 1998). Consequently, this highly debilitating and degenerative disease is often not diagnosed until late stages of the disease that present clinical and radiographic manifestations. Current treatments or therapy are only palliative and designed to reduce pain and physical disability. Most medications that are in current use non-steroidal anti-inflammatory drugs (NSAIDs) which are often ineffective and in some instances have deleterious effects on cartilage metabolism (Brandt, K., D. Rheum. Dis., North Am., 19: 697-712, 1993). Most health care providers and afflicted patients are more interested in relieving the painful symptoms and disability associated with this disease. In view of a lack of curative treatment for OA, it is imperative that any current therapy being developed for this disease be aimed at relieving these debilitating and disabling symptoms.
The biochemistry and factors that regulate the metabolism of the joint, in particular particular cartilage, are a crucial part of the scientific rationale for designing a new treatment for OA. Particular cartilage is composed of an intricate collagenous scaffold that consists mainly of type II collagen, with types VI, XI and XI collagen found in specific locations throughout the matrix (Ronziere, M. C., Ricard-Blum, S., Tollier, J. et al, Biochim. Biophys. Acta, 1038: 222-230, 1990 and Eyre, D., Wu, J. J., and Woods, P., xe2x80x9cParticular Cartilage and Osteoarthritisxe2x80x9d, (eds, Keuttner, K. E., Schleyerbach, R., Peyron, J. G., and Hascall, V. C.), pp. 119-131, Raven Press, New York, 1992). Within this matrix are found, large multi-ternary complexes, known as proteoglycan aggregates. These complexes are made up of an HA backbone and aggrecan molecules that interact specifically, in a non-covalent manner, via core protein sequences, that are also stabilized by a co-operative interaction with link protein (Goetinck, P. F., Stirpe, N. S., Tsonis, P. A., and Carlone, D., J. Cell Biol., 105: 2403-2408, 1987 and Hascall V. C., and Heinegard, D., J. Biol. Chem., 249: 4232-4241, 1974). The multiple glycosaminoglycan (GAG) chains on aggrecan are made up of mostly of chondroitin sulfate (approx. 100 chains of 15-20 kDa), and keratin sulfate (up to 50 chains of 5-8 kda) and confer the specialized viscoelastic and biomechanical properties of particular cartilage tissue (Hascall, V. C., xe2x80x9cAtlas of Science: Biochemistryxe2x80x9d, (ed. Grimmwade), pp. 189-198, New York, 1988). As such, the concentration of GAGS and their anionic character, coupled with the integrity of the collagen meshwork, are the primary parameters that define the unique Theological properties of particular cartilage (Torchia, D. A., Hasson, M. A., and Hascall, V. C., J. Biol. Chem., 251: 3617-3625, 1977). It is, therefore, important that the metabolic regulation of these molecules by chondrocytes be maintained at a level that permits the tissue to function properly.
In normal cartilage, chondrocytes actively maintain a stable equilibrium between the synthesis and degradation of matrix components. In degenerative joint diseases like OA, this equilibrium is disrupted as the rate of proteoglycan and matrix loss begins to exceed the rate of deposition of newly synthesized molecules (Handley, C. J., xe2x80x9cParticular Cartilage and Osteoarthritisxe2x80x9d, (eds, Keuttner, K. E., Schleyerbach, R., Peyron, J. G., and Hascall, V. C.), pp. 411-413, Raven Press, New York, 1992). Various factors are known to modulate and regulate proteoglycan aggregate complex metabolism in particular cartilage. Anabolic factors such as insulin-like growth factor-I (IGF-I) (Morales, T. I., and Hascall, V. C., Ann. Rheum., 32: 1197-1201, 1989; McQuillan, D. J., Handley, C. J., Campbell, M. A. et al., Biochem. J., 240: 423-430, 1986 and Luyten, F. P., Hascall, V. C., Nissley, S. P. et al., Arch. Biochem. Biophys., 267: 416-425, 1988, and growth differentiation factor-5 (GDF-5), Erlacher, L., Ng, C. K., Ullrich, R. et al., Arthr. Rheum., 41: 263-273, 1998), are of particular interest as specific mitogens that also promote the synthesis of proteoglycans and other matrix proteins in chondrocytes.
The IGFs are polypeptides that share structural and functional homology with insulin (Benito, M., Vlaverde, A. M., and Lorenzo, M., Int. J. Biochem. Cell Biol., 28: 499-510, 1996). In humans, two major IGFs isoforms are known; IGF-I (7.5 kDa) and IGF-II, that play a major part in the growth and development of many tissues during fetal and adult life. These factors are also implicated in tissue hyperthrophy and repair processes. IGF-I, a factor found in normal serum, is known to enhance the synthesis of collagen and proteoglycan in normal cartilage in vivo and in vitro (McQuillan, D. J., Handley, C. J., Campbell, M. A. et al., Biochem. J., 240: 423-430, 1986; Luyten, F. P., Hascall, V. C., Nissley, S. P. et al., Arch. Biochem. Biophys., 267: 416-425, 1988; Middleton, J. F. S., and Tyler, J. A., Ann. Rheum. Dis., 51: 440-447, 1992). Studies have shown that IGF-I increases the coordinated rate of proteoglycan, link protein and hyaluronan synthesis in adult particular cartilage explants (Luyten, F. P., Hascall, V. C., Nissley, S. P. et al., Arch. Biochem. Biophys., 267: 416-425, 1988 and Ng, C. K., Handley, C. J., Preston, B. N. et al., Arch. Biochem. Biophys., 316: 596-606, 1995).
Specific receptors for the IGF""s have been detected in rabbit, bovine and human cartilage (Tardif, G., Reboul, P., Pelletier, J. P. et al., Arth. Rheum., 39: 968-978, 1996). So far, three structurally related receptors for members of this family have been identified: the insulin receptor, the type I IGF receptor, and an orphan receptor known only as insulin receptor-related receptor or IRR, (Meyts, P. D., Wallach, B., Christoffersen, C. T. et al., Horm. Res., 42: 152-169, 1994). These three receptors belong to the receptor protein tyrosine kinase family where they constitute a subgroup with distinct features and are encoded by a single gene located on human chromosomes 19, 15 and 1, respectively. The IGF-I receptor binds IGF-I with high affinity and IGF-II with an equally high or slightly lower affinity; it binds insulin with 500-1000 times lower affinity, explaining in part the well known role of insulin as a cartilage anabolic growth factor at high concentration.
There is evidence that the type I IGF receptor may play a role in the pathogenesis of OA (Keyszer, G. M., Heer, A. H., Kriegsmann, J. et al., J. Rheumatol., 22: 275-281, 1995). This was shown both in vitro, where IGF-I was found to reduce interleukin-1 (IL-l) stimulated cartilage degradation, and in vivo in an experimental model of OA in which IGF-I, administered in a combination with a synthetic protease inhibitor (sodium pentosan polysulfate (PPS), produced significant improvement in several OA disease parameters when compared with PPS or IGF-1 alone (Rogachefsky, R. A., Dean, D. D., Howell, D. S., and Altman, R. D., Osteoarthritis Cartilage, 1: 105-114, 1993).
The present invention provides a composition for treating diseased, injured or abnormal cartilage comprising hyaluronic acid and a growth factor such that the composition has a viscosity and biodegradability sufficient to persist at the site desired growth for a period of time sufficient to alleviate the symptoms of injury, disease or abnormality. The composition is also useful for treatment of diseased injured or abnormal osteochondral tissue, such as that found in osteoarthritis.
Viscosupplementation via the administration of hyaluronic acid (HA) into the damaged tissue, in combination with a cartilage anabolic growth factor, is a novel approach for alleviating the symptoms, inhibiting the further progression, and reversing the underlying pathophysiology of OA.
As used herein, the term hyaluronic acid, abbreviated as HA, means hyaluronic acid and its salts such as the sodium, potassium, magnesium, calcium, and the like, salts.
By growth factors, it is meant those factors, proteinaceous or otherwise, which are found to play a role in the induction or conduction of growth of ligaments, cartilage or other tissues associated with joints.
In particular these growth factors include bFGF, aFGF, EGF (epidermal growth factor), PDGF (platelet-derived growth factor), IGF (insulin-like growth factor), TGF-xcex2 I through III, including the TGF-xcex2 superfamily (BMP-1 through 12, GDF 1 through 8, dpp, 60A, BIP, OF).
The processes by which the compositions and the method of their use are described in more detail. The HA is preferably uncrosslinked having a molecular weight of 500,000 and above, typically in the range of 104 to 107 daltons. The cartilage growth-promoting compositions will typically contain from about 0.01 up to 4 percent by weight of uncrosslinked HA in an aqueous solution which also contains other solution excipients such as buffer salts, sugars, anti-oxidants and preservatives to maintain the solubility and bio-activity of the growth factor and proper pH of the composition. A composition containing from about 0.1 to 2 percent by weight of uncrosslinked HA is preferred. A typical pH of the solution will be in the range of 4 to 9, preferably about 6.0xc2x11.0 and most preferably about 5.0.
Several HA preparations with different molecular weights are readily available. The molecular weight ranges of commercially available HA vary from 8xc3x97105xe2x88x927xc3x97106 Da (8xc3x97105 Da for Artz(copyright), Seikagaku Kogyo, Co. Ltd. and Hyalgan(copyright), Fidia Co. Ltd., 7xc3x97106 Da for Synvisc(copyright), Biomatrix Co. Ltd.). Typically, studies are conducted with HA purified from rooster comb, such as, HA in the range of 1-3xc3x97106 Da (Anika Therapeutics, MA).
The growth factor will typically be present in the solution in a concentration range of about 10xe2x88x926 to 100 mg/ml of solution, and particularly in the case of the IGF family of proteins or their active fragments, about 0.1 to 20 mg/ml. The concentration will be dependent upon the particular site and application, as well as the volume of the injection and specific activity of the growth factor. The preferred growth factor is IGF-I.
The utility of HA stems from the synergistic interaction with active agents that:
1) localizes and sustains the active agent at the site of injection, and;
2) increases the stability of the biologically active agents. The combination of HA with a cartilage specific anabolic factor provides not only a symptomatic relief, but also an inhibition of progression of the underlying pathophysiology of OA;
3) provide their own benefit in the treatment of OA;
4) Utilize similar and overlapping intracellular signalling pathways to facilitate a biologic response.
It is important for the solution to have a viscosity which allows it to be injectable through a syringe or catheter, but not to be prematurely diluted by the body fluids before the desired effect can be achieved. Preferably, the viscosity of the composition is within a range of 10 to 106 cP and, in the case of IFG-I containing compositions, preferably about 75,000 cP.
It is also important for the composition to have a biodegradability which is sufficient to allow it to remain in place at the site of diseased, injured or abnormal cartilage to effect the symptom alleviating activity.
The composition must usually persist at the particular site for a period from about three (3) to about thirty (30) days, typically from three (3) to about fourteen (14) days.
The compositions are typically formed as solutions by mixing the HA and growth factor in appropriate amounts of excipients such as sodium citrate, EDTA and sucrose so that the HA and growth factor remain in solution at the desired concentration and the solution exhibits the appropriate viscosity and biodegradability. The composition may also contain growth factor binding proteins, such as an IGF-I binding protein, which prolong the period of activity of the growth factor at the site of application. The solution may be applied to an particular site in any convenient manner, typically by introduction through a syringe or catheter.
Administration of a composition of the present invention may be desirable to accelerate healing, prevent further tissue damage from occurring subsequent to injury, avoid treatments that compromise the natural healing process and create optimal physical and biological conditions for healing. Typical particular sites include vertebral compression injuries, rib injuries and joint injuries. Effective dosages are typically about 10xe2x88x923 to 10xe2x88x924 xcexcg/kg of body weight of compositions containing about 0.01-4% by weight HA and about 10xe2x88x926 to 100 mg/ml of growth factor. The invention is described in more detail in the following examples, which are provided by way of illustration and are not intended to limit the invention set forth in the claims.